Putters

ABSTRACT

A set of putters, the different putters having different values of at least one of the variables which affect the suitability of the putter for short or long putts, for example loft, lie, length, coefficient of restitution of the impact face ( 22 ) and alignment aid ( 21 ).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional App. No. 60/854,228, filed 25 Oct., 2006, by Robert B. Zider.

FIELD OF THE INVENTION

This invention relates to putters.

BACKGROUND OF THE INVENTION

Golfers habitually carry a single putter and a correlated set of drivers and irons (see for example U.S. Pat. Nos. 3,655,188, 4,621,813, 5,665,009, 5,976,029, 6,196,934, 6,482,104, 6,547,675, 6,723,005, 6,860,819, 6,863, 621 and 7,022,027, the entire disclosure of each of which is incorporated herein by reference for all purposes). Much effort has been expended in the design of putters, and every golf shop contains a bewildering variety of putters from which a golfer can choose the single putter which he or she habitually carries (see for example U.S. Pat. Nos. 7,175,540, 6,471,600, 6,203,443, 5,846,140, 5,842,935, 5,839,970, 4,688,798, 4,659,083, 4,222,566, 4,383,690 and 3, 884, 477, and US patent publication Nos. 2006/009307, 2005/0192114, 2005/0187028 and 2005/0096153, the entire disclosure of each of which is incorporated herein by reference for all purposes)

SUMMARY OF THE INVENTION

We have realized, in accordance with the present invention, that a golfer can achieve improved results if he or she carries a set of at least two different putters (for example, two, three or four putters) which have different, but correlated, characteristics such that each putter is best suited for a particular type of putt. The golfer can then select the putter which is best suited to the particular putt which he or she is going to make. For example, one of the putters can have characteristics which are better suited to short putts (where direction control it is more important than distance control), and another of the putters can have characteristics which are better suited to long putts (where distance control is more important than direction control). When using a single putter for all kinds of putt, the golfer must change his swing for different lengths of putt. One advantage which can result from preferred embodiments of the present invention is that the golfer can make use of a more uniform swing, for example because the coefficient of restitution of the impact face of the putter (hereinafter abbreviated to COR) for short putts is less than the COR of the putter for long putts.

The rules of golf state that a golfer must not carry more than 14 clubs. Therefore, for golfers who habitually carry 14 clubs, one of which is a putter, carrying two or more putters will necessitate discarding one or more of the other clubs. However, since a putter is used on almost every hole, and some other clubs are comparatively seldom used, the improved putting efficiency provided by the present inventions outweighs any loss of efficiency resulting from the absence of one or more other clubs.

In a first preferred aspect, this invention provides a set of putters, the different putters having different values of at least one of the variables which affect the performance of a putter. The variables which affect the performance of a putter are for example loft, lie, length, COR and alignment aid.

In a second preferred aspect, this invention provides a method of playing golf in which the golfer carries a set of putters according to the first preferred aspect of the invention, and selects one of the set for each putt.

In a third preferred aspect, this invention provides a display of a set of putters according to the first preferred aspect of the invention, for example a display of three to nine correlated putters, from which a golfer may choose a lesser number, e.g. two or three putters, to carry in his or her golf bag. The display can be a physical display, e.g. in a shop, or a virtual display, e.g. on a web site. A golfer intending to make use of the invention can select two or three putters from such a physical display after experimenting with some or all of the displayed putters to see which best suits his or her preference. The selection process also forms part of the present invention.

The invention also includes a set of golf clubs which includes correlated woods, correlated irons and a set of putters according to the first preferred aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in the accompanying drawings, in which FIGS. 1A-1B, 2A-2B, 3A-3B, 4A-4B and 5A-5B are front and rear perspective views respectively of five putters which together form an example of a set of putters according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the Summary of the Invention above, the Detailed Description of the Invention, and the Claims below, and the accompanying drawings, reference is made to particular features (including for example components, ingredients, elements, devices, apparatus, systems, groups, ranges, method steps, test results, etc.) of the invention. It is to be understood that the disclosure of the invention in this specification includes all possible combinations of such particular features. For example, where a particular feature is disclosed in the context of a particular aspect, a particular embodiment, a particular claim, or a particular Figure, that feature can also be used, to the extent appropriate, in the context of other particular aspects, embodiments, claims and Figures, and in the invention generally. The invention disclosed herein includes embodiments not specifically described herein and can for example make use of features which are not specifically described herein, but which provide functions which are the same, equivalent or similar to, features specifically disclosed herein.

The term “comprises” and grammatical equivalents thereof are used herein to mean that, in addition to the features specifically identified, other features are optionally present. For example, a system “comprising” (or “which comprises”) components A, B and C can contain only ingredients A, B and C, or can contain not only ingredients A, B and C but also one or more other ingredients. The term “at least” followed by a number is used herein to denote the start of a range beginning with that number (which may be a range having an upper limit or no upper limit, depending on the variable being defined). For example “at least 1” means 1 or more than 1, and “at least 80%” means 80% or more than 80%. When, in this specification, a range is given as “(a first number) to (a second number)” or “(a first number)—(a second number)”, this means a range whose lower limit is the first number and whose upper limit is the second number. For example, “4.5 to 6.0” or “4.5-6.0” means a range whose lower limit is 4.5, and whose upper limit is 6.0. The terms “plural” and “plurality” are used herein to denote two or more than two features.

Where reference is made herein to “a” or “an” feature, this includes the possibility that there are two or more such features (except where the context excludes that possibility). Where reference is made herein to two or more features, this includes the possibility that the two or more features are replaced by a lesser number or greater number of features providing the same function (except where the context excludes that possibility). The numbers given herein should be construed with the latitude appropriate to their context and expression; for example, each number is subject to variation which depends on the accuracy with which it can be measured by methods conventionally used by those skilled in the art.

The different putters in a set preferably carry visible identifiers, preferably on the head of each putter, so that a golfer can easily select the appropriate putter of the set. The identifier optionally also has a functional purpose. For example, the identifier can be an alignment aid whose dimensions and/or appearance identifies the length of the putt for which the putter is appropriate.

In one embodiment, each of the putters has a different value from the other putters of each of the characteristics of loft, lie, length, COR and visual alignment aid. In another embodiment, each of the putters has a different value from the other putters of at least one characteristic selected from loft, lie, length, COR and visual alignment aid, and the same value as all the other putters of at least one characteristic selected from loft, lie, length, COR and visual alignment aid. For example, the putters can have (i) different values of loft and the same values for at least one of, e.g. each of, the other characteristics, or (ii) different values of COR and the same values for at least one of, e.g. each of, the other characteristics, or (iii) different values of loft and of COR and the same values for at least one of, e.g. each of, of the other characteristics. The putters can also be the same as or different from each other in some characteristic other than loft, lie, length, COR and visual alignment aid, for example moment of inertia of the putter around the shaft and/or around the center of gravity of the putter head.

When there is a change in the value of the loft between adjacent putters in a set, it can for example be at least 0.8° or at least 1.00, and/or at least 10% or at least 20%, e.g. 8-80% or 8-50%, based on the larger of the two values. In one preferred set of two putters, the higher value (on the putter for short putts) is 4-8°, for example 5-6°, e.g. about 5°, and the lower value (on the putter for long putts) is 1-4° (and at least 1° lower than the higher value), for example 1-3°, e.g. about 2°. In one preferred set of three putters, the highest value (on the putter for short putts) is 5-9°, for example 6-8°; the intermediate value (on the putter for medium length putts) is 3-7°, for example 4-6° (and at least 1° lower than the highest value); and the lowest value (on the putter for long putts) is 1-4°, for example 2-5° (and at least 1° lower than the intermediate value).

When there is a change in the value of the COR between adjacent putters in a set, it is often a function of the hardness of the material of the impact face. The impact face is generally substantially planar, though it can be slightly convex. The change in the value of the Shore A hardness of the material of the impact face, between adjacent putters in a set, can for example be at least 10, at least 20 or at least 30 and/or at least 10% or at least 20%, e.g. 8-80% or 8-50%, based on the larger of the two values. In one preferred set of two putters, the higher value (on the putter for long putts) is at least 80 or at least 100, the material being for example a metal or a relatively hard polymeric material, and the lower value (on the putter for short putts) is 40-80 (and at least 10 lower than the higher value), for example 40-60, the material being for example a relatively soft polymeric material. In one preferred set of three putters, the highest value (on the putter for long putts) is at least 80 or at least 100, the material being for example a metal or a hard polymeric material; the intermediate value (on the putter for medium length putts) is 50-90, for example 60-80 (and at least 10 lower than the highest value), the material being for example a less hard polymeric material; and the lowest value (on the putter for short putts) is 40-60, for example 40-50 (and at least 10 lower than the intermediate value), the material being for example a relatively soft polymeric material.

Where reference is made herein to putters having different values of COR, this includes the possibilities that

-   -   (1) each impact face has a uniform COR which is different from         the COR of each of the other impact faces, and     -   (2) at least one of the impact faces of the different putters         has a COR which varies across the impact face so that it is         different from each of the other impact faces, which may have a         uniform or varying COR.

When the COR varies across the impact face, the variation can be for example parallel to, or at right angles to, the sole of the putter. Such variation can for example be achieved in the ways disclosed in U.S. Pat. No. 5,807,190 and WO 2005/007250, the entire disclosure of each of which is incorporated herein by reference for all purposes. U.S. Pat. No. 5,807,190 discloses a golf club whose impact face comprises the end walls of a plurality of separate members (“pixels”) closely packed in a recess in the head of the golf club. The pixels can be covered by a cover member which provides the impact surface. By variation of the material and/or shape of the pixels, a desired variation in the COR across the face of the putter can be obtained. This makes it possible, for example, to reduce the variation in the distance which a putt travels when a putt is hit at the center and off-center. This is particularly important when the putt is a long one (typically, a putt will lose 5% of its distance if hit 0.5 inch (12.5 mm) off dead center, which on a 30 foot (9m) putt is about 1.5 feet (0.5 m)) and/or the putter is swung in an arc, which makes it more difficult to center the putter face on the ball. WO 2005/007250 discloses a golf club whose impact face comprises a plurality of bars which can be individually deflected, without permanent damage, in a direction perpendicular to the impact face when the impact face strikes a golf ball; the bars can be covered by a cover member which provides the impact face. Other documents which disclose ways in which the COR of an impact face can be controlled (in a uniform or desired non-uniform way) include U.S. Pat. Nos. 7,281,990, 7,273,420, 7,278,926 and 7,175,540, the entire disclosure of each of which is incorporated herein by reference for all purposes.

When there is a change in the value of the length between adjacent putters in a set, it can for example be at least 1″ (25 mm) or at least 2″ (50 mm) and/or at least 2% or at least 4%, e.g. 1-20% or 2-10%, based on the larger of the two values. In one preferred set of two putters, the higher value (on the putter for long putts) is 34-42″ (0.85-1.05 m), for example 36-39″ (0.9-1.0 m) and the lower value (on the putter for short putts) is 33-39″ (0.75-1.0 m) and at least 1″ (25 mm) lower than the higher value, for example 32-36″ (0.81-0.91 m), e.g. about 33″ (0.84 m). In one preferred set of three putters, the highest value (on the putter for long putts) is 36-42″ (0.91-1.05 m), for example 37-39″ (0.94-0.99 m); the intermediate value (on the putter for medium length putts) is 34 -38″ (0.86 -0.96 m) and at least 1″ (25 mm) lower than the highest value, for example 35-37″ (0.89 -0.94 m), e.g. about 36″ (0.91 m), and at least 1″ (25 mm) lower than the highest value); and the lowest value (on the putter for short putts) is 30-37″ (0.76-0.94m), for example 32-36″ (0.81-0.91 m), and at least 1″ (25 mm) lower than the intermediate value, for example about 34″ (0.86 m).

When there is a change in the value of the lie between adjacent putters in a set, it can for example be at least 2° or at least 5° or at least 10°, and/or at least 2% or at least 5% or at least 10%, e.g. 2-20% or 5-15%, based on the larger of the two values. In one preferred set of two putters, the higher value (on the putter for short putts) is 70-90°, for example 70-80°, and the lower value (on the putter for long putts) is 55-80°, for example 65-75° (and at least 5° lower than the higher value). In one preferred set of three putters, the highest value (on the putter for short putts) is 70-90°; the intermediate value (on the putter for medium length putts) is 60-75° (and at least 50 lower than the highest value); and the lowest value (on the putter for long putts) is 55-80°, and at least 50 lower than the intermediate value).

Alignment aids which are optionally present on some or all of the putters in a set include the alignment aids disclosed in U.S. Pat. Nos. 7,175,540, 6,471,600, 5,846,140, 5,842,935, 5,839,970, 4,688,798, 4,659,083, 4,222,566, and 3,884, 477, and US patent publication Nos. 20050192114, 20050187028 and 20050096153, the entire disclosure of each of which is incorporated herein by reference for all purposes. For example, the alignment aid can extend backwards from the face of the putter, and the length of the alignment aid can be proportional to the length of the putt for which the putter is most appropriate. Such alignment aids are shown in the accompanying drawings.

The table below shows possible values of loft, lie, length, COR and alignment aid, for sets consisting of 2 putters and sets consisting of 3 putters. In the table, the abbreviations sp, mp and lp refer to putters for short, medium and long putts respectively, and the numeral 2 or 3 refers to the number of putters in the set. For example, loft (sp3) means the loft on the putter to be used for short putts in a 3-putter set.

The various putters can have all the characteristics set out in the table below, or less than all the characteristics set out in the table below, for example only one of the characteristics, or two, three, four or five of the characteristics.

2-putter set 3-putter set sp putter lp putter sp putter mp putter lp putter Loft Loft(sp2) Loft(lp2) Loft(sp3) Loft(mp3) Loft(lp3) e.g. ≧1.0, ≦Loft(sp2) − 3°, e.g. ≧4.0°, ≦Loft(sp3) − 0.5, & ≦2.5°, e.g. e.g. 3.2°, e.g. e.g. ≦2.8°, e.g. e.g. 4.5 to ≧Loft(lp3) + 0.5 1.5 to 2.5° 4.0 to 5.5° 1.5 to 2.5° 6.0° eg . . . 2.5 to 4.5° Lie Lie(sp2) Lie(lp2) Lie(sp3) Lie(mp3) Lie(lp3) e.g. 70° to ≦Lie(sp2) − 10°, e.g. 75° to ≦Lie(sp3) − 5°, & e.g. 55° to 90° e.g. 55° to 70° 90° ≧L(lp3) + 5° 65° e.g. 65° to 75° Length Length(sp2) Length(lp2) Length(sp3) Length(mp3) Length(lp3) e.g. 32-36″ ≧Length(sp2) + e.g. 32-35″ ≦Length(lp3) − 2″ & e.g. 37-39″ (0.81-0.91 m), 2″, e.g. 36-39″ (0.81-0.89 m), ≧Length(sp3) + 2″, (0.94-1.0 m), e.g. (0.91-1.0 m), e.g. e.g. 35-37″(0.89-0.94 m), e.g. about 33″ e.g. about 38″ about 34″ e.g. about about 38″ (0.84 m) (0.96 m) (0.86 m) 36″(0.91 m) (0.99 m) COR COR(sp2) COR(lp2) COR(sp3) COR(mp3) COR(lp3) e.g. a ≧COR(sp2) + 5% e.g. a soft ≦COR(lp3) − 5%, e.g. a hard polymeric e.g. 5-20% polymeric e.g. 5-20% polymeric impact face e.g. a polymeric impact face ≧COR(sp3) + 5%, or metal or metal impact e.g. 5-20%, impact face e.g. a polymeric face impact face Alignment Strong Weak Strong Medium Weak aid

The terms “putter”, and the terms “length”, “loft” and “lie” as applied to a putter, are well understood by those skilled in the art and are used herein in accordance with the R&A Rules of Golf. Thus, “lie” is the angle between a heel-to-toe line of the putter head and the axis of the shaft; “loft” is the angle of the striking face plane from the vertical; and the length of a putter is defined herein in the same way as in the R&A Rules of Golf. The putter lies on a horizontal plane and the sole is set against a 60 degree plane. For a putter having a straight shaft, the length is defined as the distance from the point of the intersection between the two planes to the top of the grip of the putter. For a putter having a shaft which is not straight, the length is the distance from the top of the grip along a straight line extension of the axis of the shaft to the sole of the putter.

In some embodiments of the invention, each of the putters in a set of putters of the invention has at least one of (i.e. one of, or, when possible, two or more of) the following characteristics.

(1) The length of the putter is from 18 inches (457.2 mm) to 48 inches (1,219.2 mm).

(2) The length of the putter is greater than 48 inches (1,219.2 mm).

(3) All of the heel portion of the putter lies within 0.625 inches (15.88 mm) of the plane containing the axis of the straight part of the shaft and the intended (horizontal) line of play.

(3) Part of the heel portion of the putter lies more than 0.625 inches (15.88 mm) of the plane containing the axis of the straight part of the shaft and the intended (horizontal) line of play.

(4) The projection of the straight part of the shaft of the putter on to the vertical plane along the intended line of play does not diverge from the vertical by more than 20 degrees forwards or 10 degrees backwards.

(5) When the putter is in its normal address position, the shaft is so aligned that: (i) the projection of the straight part of the shaft onto the vertical plane through the toe and heel diverges from the vertical by at least 10 degrees.

(6) The shaft of the putter is straight from the top of the grip to a point not more than 5 inches (127 mm) above the sole, measured from the point where the shaft ceases to be straight along the axis of the bent part of the shaft and the neck and/or socket.

(7) At any point along its length, the shaft of the putter, (i) if it bends at all, bends in such a way that the deflection is the same regardless of how the shaft is rotated about its longitudinal axis; and (ii) if it twists at all, twists the same amount in both directions.

(8) The shaft of the putter is attached to the putter head at the heel either directly or through a single plain neck and/or socket and the length from the top of the neck and/or socket to the sole of the putter is at most 5 inches (127 mm), measured along the axis of, and following any bend in, the neck and/or socket.

(9) The shaft of the putter is attached to the putter head at the heel either directly or through a single plain neck and/or socket and the length from the top of the neck and/or socket to the sole of the putter is more than 5 inches (127 mm), measured along the axis of, and following any bend in, the neck and/or socket.

(10) The grip of the putter consists of material added to the shaft to enable the player to obtain a firm hold, is straight and plain in form, extends to the end of the shaft and is not molded for any part of the hands. If no material is added, that portion of the shaft designed to be held by the player is considered the grip.

(11) The grip of the putter is circular in cross-section, except for the optional presence of a continuous, straight, slightly raised rib along the full length of the grip, and/or a slightly indented spiral on a wrapped grip or a replica of a wrapped grip.

(12) The grip of the putter has a cross-section which is non-circular, has no concavity, is symmetrical and remains generally similar throughout the length of the grip.

(13) The grip is not tapered, or is tapered without any bulge or waist, and has a cross-sectional dimension measured in any direction of at most 1.75 inches (44.45 mm).

(14) The grip of the putter has an axis which coincides with the axis of the shaft of the putter.

(15) The putter has two grips, each grip being circular in cross-section and having an axis which coincides with the axis of the shaft, and the grips being separated by at least 1.5 inches (38.1 mm).

(16) The head of the putter does not comprise

-   -   (i) holes through the head,     -   (ii) transparent material added for other than decorative or         structural purposes,     -   (iii) appendages to the main body of the head such as knobs,         plates, rods or fins, for the purpose of meeting dimensional         specifications, for aiming or for any other purpose.

(17) The head of the putter does comprise one or more of

-   -   (i) holes through the head,     -   (ii) transparent material added for other than decorative or         structural purposes,     -   (iii) appendages to the main body of the head such as knobs,         plates, rods or fins, for the purpose of meeting dimensional         specifications, for aiming or for any other purpose.

(18) The sole of the putter does not comprise furrows in the sole or runners on the sole which extend into the face.

(19) The dimensions of the head of the putter are such that, when the head is in its normal address position, the distance from the heel to the toe is greater than the distance from the face to the back, the distance from the heel to the toe being measured (i) on horizontal lines between vertical projections of the outermost points of the heel and the toe or (ii) at the face; and the distance from the face to the back being measured on horizontal lines between vertical projections of the outermost points of the heel and the toe.

(20) The head of the putter has only one striking face.

(21) The head of the putter has two striking surfaces, the striking surfaces having the same characteristics and being opposite each other.

(22) The impact area of the putter is hard and rigid.

(23) The impact area of the putter is not hard and rigid.

(24) The impact area of the putter is smooth and does not have any degree of concavity.

(25) The surface roughness of the impact area of the putter does not exceed that of sandblasting, or of fine milling.

(26) The whole of the impact area is of the same material.

(27) The impact area of the putter is composed of a metal.

(28) The impact area of the putter is composed of a material which is not a metal.

Referring now to the drawings, each of the Figures shows the bottom part of a putter having a shaft 1 and a head 2 having an alignment aid 21 and an impact face 22 comprising a multiplicity of pixels. The putters shown are designed for progressively longer putts, with the putter in FIGS. 1A-B being designed for the shortest putts, and the putter shown in FIGS. 5A-B being designed for the longest putts. The loft on the different putters can be the same or, preferably, can decrease progressively (in a regular or irregular fashion) from the putter shown in FIGS. 1A-B to the putter shown in FIGS. 5A-B. The hardness of the impact face on the different putters can be the same or, preferably, can increase progressively (in a regular or irregular fashion) from the putter shown in FIGS. 1A-B to the putter shown in FIGS. 5A-B. The length and lie of the different putters can be the same or, preferably, can change progressively (in a regular or irregular fashion) from the putter shown in FIGS. 1A-B to the putter shown in FIGS. 5A-B. 

1. A set of putters, each of the putters having different values of at least one characteristic selected from loft, lie, length, coefficient of restitution and visual alignment aid.
 2. A set of putters according to claim 1 wherein each of the putters has different values of each of the characteristics of loft, lie, length, coefficient of restitution and visual alignment aid.
 3. A set of putters according to claim 1 wherein all the putters have the same value of at least one of the characteristics of loft, lie, length, coefficient of restitution and visual alignment aid.
 4. A set of putters according to claim 1 wherein each of the putters has a loft which is different from the loft of each of the other putters.
 5. A set of putters according to claim 1 wherein each of the putters has an impact face whose coefficient of restitution is different from the coefficient of restitution of the impact face of each of the other putters.
 6. A set of putters according to claim 1 which consists of four, five, six, seven, eight or nine putters displayed for sale in a shop.
 7. A method of playing golf in which a golfer carries a set of putters, each of the puffers having different values of at least one characteristic selected from loft, lie, length, coefficient of restitution and visual alignment aid, selects one of the putters for each putt, and uses the selected putter to make the putt.
 8. A set of clubs which includes correlated woods, correlated irons and a set of putters as claimed in claim 1, the set consisting of two or three puffers.
 9. A method of selecting a set of putters as claimed in claim 1 the set consisting of two or three putters, the method comprising experimenting with at least three putters from a set of putters as claimed in claim 1 and selecting two or three putters for use.
 10. A set of putters according to claim 1 wherein each of the putters has a different value of a characteristic selected from one or more of loft, visual alignment aid and coefficient of restitution, and all the putters have the same value of the other characteristics selected from loft, lie, length, coefficient of restitution and visual alignment aid.
 11. A set of putters according to claim 10, which consists of two or three putters.
 12. A set of putters, each of the putters having different values of at least one characteristic selected from loft, lie, length, coefficient of restitution and visual alignment aid; the loft of each of putter being from 1.5 to 6°; and the lie of each putter being from 55 to 90°; the length of each putter being from 32 to 39 inches.
 13. A set of putters according to claim 12, the set consisting of a first putter and a second putter; the first putter having a loft 4.0 to 5.5°, a lie of 70 to 90° and a length of 32 to 36 inches; and the second putter having a loft of 1.5 to 2.5°, a lie of 55 to 70° and the length of 36 to 39 inches.
 14. A set of putters according to claim 13 wherein the first putter has a polymeric impact face, and the second putter has a coefficient of restitution, which is equal to the coefficient of restitution of the first putter plus 5-20%.
 15. A set of putters according to claim 12, the set consisting of a first putter and a second putter, and the first putter having a relatively strong alignment aid in the second putter having a relatively weak alignment aid.
 16. A set of putters according to claim 12, the set consisting of a first putter, a second putter and a third putter; the first putter having a loft 4.0 to 6.0°, a lie of 75 to 90and a length of 32 to 35 inches; the second putter having a loft of 2.5 to 4.5°, a lie of 65 to 75° and the length of 35 to 37 inches; and the third putter having a loft of 1.5 to 2.50, a lie of 55 to 65° and a length of 37 to 39 inches.
 17. A set of putters according to claim 16 wherein the first putter has a polymeric impact face, the second putter has a polymeric impact face and third putter has a metallic impact face. 